DE102007037777A1 - Piezoelectric bender actuator for use in ink jet printer, has electrical contact pin electrically contacted with free outer side of piezoelectric body over contacting bridge using adhesive material in clamping region - Google Patents

Abstract

The actuator (2) has a piezoelectric body (6) attached to a carrying body (4), which extends outside over the piezoelectric body. A piezoelectrically inactive clamping region (8) is provided outside the piezoelectric body. An electrical contact pin (12) is electrically contacted with a free outer side (16) of the piezoelectric body over a contacting bridge (14) using a conductive adhesive material (18) in the clamping region. The contact pin is electrically contacted with the piezoelectric body directly over a conductive adhesive bridge in the form of contacting bridge. An independent claim is also included for a method for contacting a piezoelectric body of a piezoelectric bender actuator with a contact pin.

Description

The The invention relates to a piezoelectric bending transducer and a Method for contacting a mounted on a support body piezo body a piezoelectric bending transducer.

Piezeoelektrische Bending transducers usually include a particular oblong Supporting body, on the at least one piezoelectric body is arranged. The piezo body is in the simplest case a piezoelectrically active layer Piezoceramic placed on the support body is applied. Instead of a single piezoelectric active Layer can also be provided a multilayer structure.

Of the Piezoelectric bending transducer converts a voltage applied to the piezoelectric body Control voltage in a mechanical bending movement to. For such a piezoelectric bending transducer, there are a variety of technical Applications. Thus, the bending transducer, for example, in a piezoelectric Printer head for an inkjet printer, as a sound pickup or generator for microphones or speaker, as a sensor for Acceleration or pressure measurement, as a positioning or positioning element (Actuator), in braille lines in readers for the blind, in textile machines or used in pneumatic valves.

Of the Bending transducer is this usually in a specified by the particular application housing clamped. To damage the Piezo body, usually a piezoactive ceramic, to avoid, has the bending transducer in the connection to the piezoelectric body a piezoelectrically inactive region, with which the bending transducer is clamped.

The for the Actuation of the bending transducer required contacting takes place this usually about this inactive area. On this are Kontaktan connections, for example in shape of connection pads, applied, which contacted with the piezoelectric body Need to become.

Of the Invention is based on the object, a simple contact such contact connections with the piezo body to enable also with the dynamic loads that the bending transducer in is exposed to its normal operation, is permanently reliable.

The The object is achieved by a piezoelectric bending transducer having the features of the claim 1. This comprises a piezoelectric body, the on a support body is applied. The supporting body extends over the piezo body out. Outside of the piezo body the bending transducer has a piezoelectrically inactive clamping region in which an electrical contact connection is provided. Of the Contact connection is in this case with a free outside of the piezoelectric body after Type of over contact via a contacting bridge contacted. The contacting takes place here by means of an adhesive material.

by virtue of the use of an elastic adhesive material is a permanent one ensures secure contact even with dynamic loads. An intimate contact at the contact surfaces is permanently ensured, so that a low contact resistance Permanently ensured between the contact terminal and the piezoelectric body is.

in the Comparison to a contacting, for example by means of a screen printing process Therefore, especially in the dynamic load special Advantages. In an applied with a screen printing contact namely the danger that breaks the Kontaktierungsbrücke due to the dynamic load. Furthermore exists in bending transducers, in which the support body has a conductive central position forms, the danger that an unwanted electrical short-circuit contact between the support body opposite outside and the supporting body facing inside of the ceramic piezoelectric body is formed.

According to one expedient development, a conductive adhesive material is used. This will easily a low contact resistance over the Contact bridge achieved at the same time elastic contacting, so that a good electrical connection between the contact connection and the piezo body which can withstand dynamic loads.

Conveniently, becomes a contacting bridge an adhesive bridge used so that the contact terminal with the piezoelectric body immediately above the conductive Adhesive material is connected. This is achieved, for example, by the fact that a conductive adhesive is applied directly to the contact terminal with the piezo body combines. Alternatively, one with the conductive adhesive material coated carrier tape or coated carrier film on the piezo body and the contact connection are glued. Such adhesive tapes are commercially available by the meter. Even conductive adhesives that are viscous to paste type, are commercially in diverse variants available.

As an alternative to the direct connection between the piezoelectric body and the contact connection, an indirect connection is provided via the particularly conductive adhesive material, where in addition, an additional electrical conductor, such as a metal strip or a wire is used as an additional component. This additional electrical conductor is here glued to the piezoelectric body with the help of the conductive adhesive material, the conductive adhesive. In addition, the conductor is preferably also adhesively bonded to the contact connection, so that it is electrically connected at both ends via an adhesive connection to the contact connection or to the piezoelectric element.

Around a reliable one To ensure contact with low contact resistance the conductor preferably has at least one contact tip, with the contacting by direct contact with the piezoelectric body and / or with the contact connection. The not necessarily conductive adhesive material ensures this a secure mechanical attachment of the conductor.

According to one preferred embodiment is the contact terminal on a piezoinaktive layer arranged, which in turn is applied to the support body. hereby is an undesirable one electrical contact of the support body avoided. This is the piezoinactive layer also electrically non-conductive at the same time. Furthermore, in this case, the supporting body is not directly, but only indirectly via clamped the piezoinactive layer. Finally, the height difference between the contact terminal and the piezoelectric body is reduced and preferably Completely balanced, so that the Kontaktierungsbrücke be flat can and does not have to bridge a height level. This is particularly advantageous for dynamic loads.

Conveniently, the bending transducer is furthermore designed as a so-called trimorphic bending transducer, at the both sides of the support body one piezoelectric body each is appropriate. Each of the piezo bodies is over here contacted a contacting bridge.

The Task is according to the invention still solved by a method having the features of claim 9. The with regard to the bending transducer mentioned advantages and preferred embodiments are mutatis mutandis, too to transfer the procedure. Preferred embodiments of the method are laid down in the subclaims.

Embodiments of the invention are described below with reference to the 1 and 2 explained in more detail. The two figures each show in a schematic and greatly simplified longitudinal cross-sectional view of a piezoelectric bending transducer two alternative electrical contacts between a contact terminal and a piezoelectric body of the bending transducer.

The bending transducer shown in the figures, respectively 2 includes a longitudinally extending support body 4 , on the opposite flat sides in each case a piezoelectric body 6 is applied from a piezoelectrically active material. The bending transducer 2 has at its one end a clamping area 8th which is piezoelectrically inactive. In the clamping area 8th is on the support body 4 on both sides each piezoelectric inactive material as a piezoelectric active layer 10 applied. As a piezoelectric body 6 a piezoelectrically active ceramic is used. For the support body 4 Different materials can be used, which are also electrically conductive if necessary. As a piezoinactive layer 10 For example, a piezoin-active ceramic layer is applied, which also forms an electrical insulator.

On the piezoinactive layer 10 are formed according to the type of connection pads contact terminals 12 applied, which are connected in a manner not shown here via an electrical control line to a control unit. About this control unit of the bending transducer is applied with a suitable control voltage, so that the desired mechanical movement of the bending transducer is achieved. In the application case here is the bending transducer 2 with its clamping area 8th clamped in a housing or a holder. That with the piezo body 6 provided free end is at a control perpendicular to the longitudinal extent of the bending transducer 2 , ie within the paper plane, deflected upwards or downwards. This mechanical movement is used, for example, for controlling valves.

For the desired deflection of the piezoelectric body 6 be charged with the electrical control voltage. For this purpose, an electrical connection between the contact terminals 12 and the piezo body 6 required.

This is in both variants each with a Kontaktierungsbrücke 14 achieved, the type of over-contacting the contact terminals 12 each with a free outside 16 of the piezo body 6 combines.

The contacting bridge is in this case by means of a conductive adhesive material 18 , in particular a so-called conductive adhesive, formed. In the embodiment of 1 there is an indirect contact between the contact terminal 12 and the piezo body 6 with the help of a leader 20 , For example, a conductive metal foil, in particular copper foil. The leader 20 is both at the contact connection 12 as well as on the piezo body 6 with the aid of the preferably conductive adhesive material 18 is introduced. Preferably, in this case, the procedure is such that the conductive adhesive material 18 only immediately before the formation of the contacting bridge 14 either on the ladder 20 or on the contact connection or the piezoelectric body 6 is applied. During the curing time of the adhesive material 18 if necessary, becomes the leader 20 against the bending transducer 2 pressed, so that a good adhesive bond is formed with a sufficiently large contact surface. Additionally or alternatively, it is also possible during the curing time to expose the splice to an elevated temperature, for example by local thermal radiation.

As an alternative to the illustrated embodiment, the conductor 20 not shown contact points provided via the direct contact contact with the piezoelectric body 6 and / or with the contact connection 12 is trained. The contact tips are quasi embedded in the adhesive material to ensure a good mechanical and electrical connection.

In the embodiment of 2 becomes the contacting bridge 14 directly through the conductive adhesive material 18 educated. For this purpose, the contacting bridge 14 as an adhesive bridge 22 formed, wherein the adhesive material, the contact terminal 12 with the piezo body 6 connects directly. The adhesive bridge 22 can either exclusively from the conductive adhesive material 18 consist. Alternatively, the conductive adhesive material 18 applied to a tape or film-like carrier, so that a kind of adhesive film is formed, which is simply glued. Such an adhesive film or adhesive tape is usually provided by the meter.

Such, to the 1 and 2 described contacting using the conductive adhesive material 8th ensures a permanently secure electrical contact between the contact connection 12 and the piezo body 6 even with dynamic loads. In particular, with the contacting bridge formed in this way 14 an unintentional contacting of the support body 4 safely excluded.

2

bending transducer

4

supporting body

6

piezo body

8th

clamping

10

piezoinaktive layer

12

Contact Termination

14

contacting bridge

16

free outside

18

adhesive material

20

ladder

22

adhesive bridge

Claims (13)

Piezoelectric bending transducer ( 2 ) with a piezoelectric body ( 6 ) mounted on a support body ( 4 ) is applied, which extends over the piezoelectric body ( 6 ), wherein outside of the piezoelectric body ( 6 ) a piezoelectrically inactive clamping area ( 8th ) is provided, in which an electrical contact connection ( 12 ) arranged with a free outer side ( 16 ) of the piezo body ( 6 ) via a contacting bridge ( 14 ) with the aid of an adhesive material ( 18 ) is electrically contacted. Bending transducer ( 2 ) according to claim 1, wherein the adhesive material ( 18 ) is conductive. Bending transducer ( 2 ) according to claim 2, wherein the contact terminal ( 12 ) with the piezoelectric body ( 6 ) directly via a conductive adhesive bridge ( 22 ) as a contacting bridge ( 14 ) is electrically contacted. Bending transducer ( 2 ) according to claim 1 or 2, wherein by means of the adhesive material ( 18 ) an electrical conductor ( 20 ) on the piezoelectric body ( 6 ) is glued. Bending transducer ( 2 ) according to claim 4, wherein the electrical conductor ( 20 ) with the aid of the adhesive material ( 18 ) also on the contact connection ( 12 ) is glued. Bending transducer ( 2 ) according to one of claims 4 or 5, in which the electrical conductor ( 20 ) a contact tip for contacting with the piezoelectric body ( 6 ) and / or with the contact connection ( 12 ) having. Bending transducer ( 2 ) according to one of the preceding claims, in which the contact connection ( 12 ) on a piezoinactive layer ( 10 ) is arranged on the support body ( 4 ) is applied. Bending transducer ( 2 ) according to one of the preceding claims, in which both sides of the supporting body ( 4 ) Piezo body ( 6 ), each via a contacting bridge ( 14 ) are contacted. Method for contacting a person on a support body ( 6 ) attached piezo body ( 6 ) of a piezoelectric bending transducer ( 2 ) with a contact connection ( 12 ) outside the piezo body ( 6 ) in a piezoelectrically inactive clamping area ( 8th ), wherein a contacting bridge ( 14 ) between the electrical contact terminal ( 12 ) and a free outside ( 16 ) of the piezo body ( 6 ) with the aid of a particularly conductive adhesive material ( 18 ) is formed. Method according to Claim 9, in which the contact connection ( 12 ) directly over the adhesive material ( 18 ) with the piezoelectric body ( 6 ) is connected. Process according to claim 9, in which by means of the adhesive material ( 18 ) an electrical conductor ( 20 ) is glued. Process according to claim 11, in which immediately before the formation of the contacting bridge ( 14 ) the adhesive material ( 18 ) on the ladder ( 20 ) and / or on the piezoelectric body ( 6 ) and then the conductor ( 20 ) is glued. Method according to one of claims 9 to 12, wherein during curing of the adhesive material ( 18 ) the adhesive is loaded with pressure and / or exposed to an elevated temperature.